There are two categories that corn grown in the US is generally placed into. "Sweet" corn and "field" corn. The sweet variety is what you are used to eating. The field variety is used to feed animals, make alcohol, and in some commercially processed foods like breakfast cereals.
When distilling alcohol from corn the starches are used. If the remaining "distiller's grain" byproduct is fed to beef there is no loss in nutritional value. Cattle have a rumen, which removes the starch as waste anyway.
That's largely a matter of opinion, but most farmers will agree that hybrids will outperform open-pollinated varieties virtually every time. There are a number of different hybrids available in the US aimed at different growing areas and conditions from which each farmer selects. Most farmers base their decisions on the economic factors for their particular farm, since the cost of each variety can be quite variable.
"The ball rolled on the field" is correct. "In the field" suggests that the ball is physically inside something, like a container or enclosed area, rather than rolling freely on the surface.
Field corn is one of the most important sources for feed. Cattle, hogs and even chickens use it.
they did the turkey in the corn field
No. To make Popcorn you must use Popcorn, which is a specific variety, just like sweet corn and field corn
A "corn field".
If they do they'd be dealt with in the field by use of insecticides.
You detassel field corn to prevent cross-pollination, often from an adjacent field where seed corn is being grown.
You can, but if they pollinate at the same time, the sweet corn will taste all starchy and not sweet because it crossed with the field corn.
Here is a link to a picture of field corn: http://www.bigoo.ws/backgrounds/food/off-the-cob-field-corn-179995.htm
Feeder corn is left in the field longer to "dry down". It is sometimes Novmber before it is finally harvested.
Field corn, which is sometimes known as dent corn.
magnets?A magnetic field surounds the entire Earth, so figure it out from this hint.